In prior art cascade development arrangements, large quantities of developer are directed at the xerographic drum and circulate throughout the system at relatively high velocity, which produces developer wear owing to abrasion. Furthermore, the conveyer belts for conveying toner from lower portions of the system to upper portions for re-application to the drum normally operate at relatively high speeds of about 24 buckets per second. It is highly desirable to employ a belt conveyer which operates at considerably lower speeds to reduce wear and accompanying maintenance. In cases where an elongated development electrode defining a narrow development zone is utilized, it is highly desirable to maintain a constant pressure head of developer at the entrance of the narrow development zone in order to rapidly fill the zone upon start-up and maintain a relatively constant flow rate and constant conditions of partial toner turbulence.
The above-mentioned prior art developer conveyers additionally have toner mixers associated therewith to produce mixing of fresh toner with depleted carrier beads. This apparatus is relatively elaborate since such mixing must occur rapidly due to the above-mentioned high speed of the conveyers which are required to maintain high developer throughput velocity. It is deemed desirable to eliminate toner mixing apparatus associated with a conveyer belt and to substitute simpler toner dispensing and mixing apparatus which need not provide the relatively rapid and thorough mixing otherwise required.